The purpose of this project is to study ways in which the development of the nervous system is influenced by early experience. The system chosen for study is the kitten visual system, which has been shown to be subject to environmental modification during early life. Kittens will be exposed to a variety of controlled, specialized visual experience during the first few weeks of life. Subsequently the neurophysiological properties of visual cortex will be analyzed by means of single-unit recording, to determine receptive field organization, ocular dominance, and other physiological properties. Adult cats will also be given comparable experiences and studied in the same way, to determine the relative importance of the visual environment in early life and in adulthood.